In the completion and the production of hydrocarbons from wells, it is frequently necessary to isolate a portion of the well using a well tool, such as a packer, plug, tubing hanger and the like, supported in the wellbore at a subterranean location. These tools are lowered into the well in a retracted state called the “run position” and in a process called “setting”, the gripping means and packing means are radially expanded to a “set position” wherein the slips means and packing means engage the wellbore. A variety of types of gripping means are well known in the art and, in the illustrated embodiment, a slip means with wedge-shaped slip elements is described. Typically, packing means have resilient annular members mounted on the tool to move axially to pack off or seal the annulus around the tool. In the disclosed embodiment, the packing means comprise one or more resilient annular packing elements which, depending on the use environment, may also comprise back up and/or anti-extrusion rings. When these packing elements are axially compressed, they expand radially from the mandrel into contact with the wellbore. To hold these tools in place in the wellbore against movement, slip means typically are mounted on the tool. These slip means, like the packing means, expand radially to grip the wellbore when forced to compress axially.
Axially directed forces are used to axially compress the packing elements and slip assemblies. Such forces are typically generated by moving the tubing string; initiating an explosive charge; or applying pressure to the tool. Examples of tools that are set by manipulating the tubing string include weight down and tension packers. A weight down packer is one in which force generated by the weight of the tubing string above the tool is used to set (expand) the packing and slip element and to hold the tool in set condition. In a tension packer, the tubing string is placed in tension and that tension force is used to set and hold the tool in the set condition.
Weight down and tension packers typically comprise a hollow tubular mandrel which is connected to the tubing string. Mounted on the mandrel are the axially compressible packing elements adjacent to the slip assembly. An annular tool element called a “drag block assembly” is located on the mandrel, adjacent the slip assembly on the opposite side from the packing elements. In weight down tools, the drag block is located below the slip means and, in the tension packer, the drag block is located above the slip mean.
Certain terminology may be used in the following description for convenience only and is not limiting. For instance, the words “inwardly” and “outwardly” are directions toward and away from, respectively, the geometric center of a referenced object. Note that as used herein, “below”, “down”, “downward”, or “downhole” refers to the direction in or along the wellbore away from the wellhead whether the wellbore's orientation is horizontal, toward the surface or away from the surface. The terms “above,” “up,” “upward” or “uphole” indicates the direction in and along the wellbore toward the wellhead, whether the wellbore's orientation is horizontal, toward the surface, or away from the surface. As used herein, the term “J-slot tool” refers to a tool having a sleeve receptacle with a fitted, male element that has pins that fit into J-shaped slots on the sleeve. The J-shaped slots have short and long sides or legs. The short sides of the j-slots provide a shoulder for limiting relative movement between the pin and the sleeve. When the male element is moved up or down, depending on the orientation of the slot, and turned relative to the sleeve, the pins slide in the slot towards the long side of the J, which is open ended or long. The pins are released to move the length of the long side, thus releasing the sleeve for movement. The releasing procedure is called “unjaying the tool.” In some embodiments, the location of the pin and slot is reversed with the pin located on the sleeve. As used herein, the term “synthetic material” refers to materials that are not of natural origin and that are prepared or made artificially, using synthesis by combining separate elements or by modifying elements.
Drag block assemblies typically frictionally engage the wellbore. Drag block assemblies are mounted to slide axially on the mandrel. Movement of drag block on the mandrel is commonly limited by a pin in a J-slot. By axially moving and rotating the tubing string counter clockwise, the pin can be moved from the short leg of the J-slot to the long leg where axially moving the tubing string causes the drag block assembly to set the slip assembly and packing elements.
Conventional prior art packers utilize complicated, expensive drag block assemblies made from heavy metallic with metallic springs that engage the wellbore. An example of a prior art weight down packer of this type is illustrated in U.S. Pat. No. 4,590,995, which is incorporated by reference herein for all purposes. Examples of commercial versions of these tools are marketed by Halliburton as Champ® V Packer and Pin Point Injection (PPI) Packer. A conventional tension packer is illustrated in U.S. Pat. No. 3,422,898, which is incorporated by reference herein for all purposes.
Thus, there are needs for improved methods and apparatus for setting well tools, including providing a simple, cost-effective, improved drag block assembly that can be used with packers and other well tools.